Disclosed are methods, systems, devices, apparatus, media, and other implementations, including a method for digital predistortion for a power amplifier system. The method includes determining one or more system characteristics for the power amplifier system comprising at least a power amplifier that produces output with non-linear distortions, with the one or more system characteristics corresponding to an estimate for a complex load metric for the power amplifier system coupled to a load. The method further includes determining, based on the one or more system characteristics corresponding to the estimate for the complex load metric, digital predistortion (DPD) coefficients to compensate for the nonlinear behavior of the power amplifier system.

An envelope tracking (ET) amplifier circuit is provided. The voltage mDPD circuit is provided in an ET amplifier circuit and configured to determine a voltage deviation relative to an ET modulated target voltage signal, execute an mDPD polynomial in one or more iterations to extract an mDPD coefficient(s), and adjust a time-variant target voltage envelope of the ET modulated target voltage signal based on the mDPD coefficient(s) extracted in each of the mDPD iterations to reduce the voltage deviation to a predefined threshold. By reducing the voltage deviation in the ET modulated voltage, it is possible improve linearity (e.g., gain linearity) of the ET amplifier circuit, which can lead to reduced power consumption and improved radio frequency (RF) performance.

A RF-digital hybrid mode power amplifier system for achieving high efficiency and high linearity in wideband communication systems is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier in the RF domain. The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers and multi-channels. As a result, the digital hybrid mode power amplifier system is particularly suitable for wireless transmission systems, such as base-stations, repeaters, and indoor signal coverage systems, where baseband I-Q signal information is not readily available.

The present invention addresses method, apparatus and computer program product for stabilization of the direct learning algorithm for wideband signals. Thereby, a signal to be amplified is input to a pre-distorter provided for compensating for non-linearity of the power amplifier, and the pre-distorted output signal from the pre-distorter is forwarded to the power amplifier. Parameters of the pre-distorter are adapted based on an error between the linearized signal output from the power amplifier and the signal to be amplified using an adaptive direct learning algorithm, and the linear system of equations formed by the direct learning algorithm are solved using a conjugate gradient algorithm, wherein, once per direct learning algorithm adaptation, at least one of the initial residual and the initial direction of the conjugate gradient algorithm are set based on the result of the previous adaptation.

A method for distortion compensation in a transmission link comprising obtaining information of an amplitude distribution of a signal prior to being transmitted by a transmitter, receiving the transmitted signal at a receiver and determining a received signal amplitude distribution, comparing the received signal amplitude distribution to the amplitude distribution of the signal prior to transmission and using results of the comparison to estimate the AM/AM non-linearity in the transmitter.

Disclosed is a transmission scheme for transmitting a first modulated signal and a second modulated signal over the same frequency at the same time. According to the transmission scheme, a precoding weight multiplying unit multiplies a baseband signal after a first mapping and a baseband signal after a second mapping by a precoding weight and outputs the first modulated signal and the second modulated signal. In the precoding weight multiplying unit, precoding weights are regularly hopped.

Embodiments may relate to digital predistortion (DPD). DPD logic may identify whether the wireless signal output power of a wireless signal that is to be transmitted is above a power threshold. The signal output power is over (or, in some embodiments, equal to) the power threshold, then the DPD logic may operate in accordance with a pre-stored DPD mode wherein DPD is performed on the wireless signal based on one or more pre-stored DPD coefficients. If the signal output power is under (or, in some embodiments, equal to) the power threshold, then the DPD logic may operate in accordance with a continuously-updated DPD mode. Other embodiments may be described or claimed.

A method for synchronizing radio frequency carrier correction of dynamic radio frequency carriers is provided. The method includes receiving a carrier configuration from a carrier controller to modulate a carrier signal based on the carrier configuration and receiving a time reference and timestamped carrier configuration information from the carrier controller. The timestamped carrier configuration information includes a correlation between a plurality of timestamps and a plurality of carrier attributes. The method also includes synchronizing an internal clock of a RF correction preprocessor to the time reference, and receiving a modulated carrier signal from the RF modem. The method further includes generating a radio frequency correction set including a correction solution for each of a plurality of timeslots based on the timestamped carrier configuration information, and generating a corrected carrier signal based on applying the RF correction set to the modulated carrier signal at a coincident timeslot.

A method comprises obtaining a transmission signal to be power-amplified in a power amplifier (361) prior to transmission; separating the transmission signal into two or more polyphase components of the transmission signal; feeding one or more polyphase components of the transmission signal comprised in the two or more polyphase components to each of two or more parallel predistortion circuits (320,321,322); selecting a dedicated predistortion model and dedicated predistortion coefficients for each of the two or more parallel predistortion circuits (320,321,322); performing non-linear memory-based modeling on the transmission signal according to the selected dedicated predistortion models and coefficients using the one or more polyphase components; and combining output signals of the two or more parallel predistortion circuits (320,321,322) to form a predistorted transmission signal (y[n]) to be applied to the power amplifier (361).

The disclosure provides a transmitter of a communication system using hybrid digital/analog beamforming and configured to perform digital pre-distortion (DPD). In an exemplary embodiment in accordance with the disclosure, the transmitter may generate a plurality of scrambling sequences. The transmitter may comprise a plurality of combining modules to receive a combined feedback signal. The transmitter may use the plurality of scrambling sequences to recover the signals output by the antenna arrays from the combined feedback signal. Thus, the transmitter may perform DPD for each antenna array.